Method of and means for bending pipe



C. CROSS April 12-, 1949.

April 12, 1949. C, CROSS METHoD oF AND MEANs FOR BENDING PIPEs 5Sheets-Sheet 3 Filed NOV. 8, 1943 April 12, 1949. C, CROSS METHOD oF ANDMEANs FOR BENDING PIPEs 5 Sheets-Sheet 4 Filed Nov. 8,.1943

wuem/to CL NT Czzoss pfil 12, 1949. C CROSS 2,466,877 v VMETHOD OF ANDMEANS FOR BENDING PIPES 5 sheets-sheet 5 lill Filed Nov. 8, 1943 rWen/Lov KL INT CRoss Patented Apr. 12, 1949 Ma'rnon or AND MEANs roanENmNG rrra v cum cross, runs, 'okngmigmr to w. c. Non-h, Manufacturer,Inc., Tulsa, Okla.

Application November s, 1943, semi No. 509.446

7 ciaims; (ci. iso-'48) l This invention relates to new and usefulimprovements in methods of and means for bending pipe.v

One object of the invention is to provide an improved method wherebypipe-bands may be produced from straight lengths of pipe and theoriginal area and wall thickness of the pipe be substantially retained,with the provision of long gr short tangents at each or either end ofthe end.

A particular obiect of the invention is to provide an improved methodwhereby pipe-bends may be forged with a short radius and a short or longtangent, as desired, at each or either end while retaning substantiallythe original wall thickness in the outer medial portion of the bend.

An important'object of the invention is to provide a method, of thecharacter described, wherein the wall which is of greatest radius issupported during the bending step and at the same time is cooled, thusassuring uniform thickness.

Still another object of the invention is to provide an improvedpipe-bending or pipe-turn forming apparatus including a forming die ormandrel adapted to be inserted in the pipe and having a configurationarranged to support the wall of the pipe during the bending operation,whereby uniform flow of the metal and substantial retention of theoriginal wall thickness is obtained.

A further object of the invention is to provide an apparatus, of thecharacter described, having a displaceable preforming or breakdown diefor starting the bend and finishing dies working in sequence with thepreforming die so as to assure uniformity and continuity in the formingof the pipe-bend.

A construction designed to carry out the invention will be hereinafterdescribed together with other features of the invention.

The invention Will be mdre readily understood from a reading of thefollowing specification and by reference to the accompanying drawings,wherein an example of the invention is shown. and wherein:

Figure 1 is an isometrical view of an apparatus constructed inaccordance with the invention and shown in an open position-with thepreforming die in Operating position,

Figure 2 is a view, partly in plan and partly in section, of portion ofthe apparatus showing the parts in position after the bend has beencompleted.

Figure-3 is an elevation of the forming die or mandrel,

Figures 4, 5, 6 and 7 are transverse. vertical,

2 sectional views, taken on the lines l-l, 5-5, I-l and 1-1,respectively, of Figure 3,

Figure 8 is a plan view of a modified form of apparatus in openposition,

Figure 9 is a similar view, partly in plan and partly in section,showing one of the mandrels r in the pipe-bend, the preforming die'abeing omitted. I

Figure lo is a similar view, showing the other mandrel in the pipe-bend,

Figure 11 is a view, similar to Figure 10, 'showing mandrels forupsetting the outer medial portion of the pipe-bend, g

Figure 12 is a similar view showing the upsetting mandrels in engagementand the outer medial portion of the pipe-bend upset,

Figure 13 is a longitudinal, vertical, sectional view of one of themandrels and its cylinder, showing the mounting thereof, and

Figure 14 is an elevation of a pipe-bend, the dotted lines showing theshape after the bend is completed with the ends, after being cut, beingshown in full lines.

In the drawings, the numeral lll designates in all of the flgures thebed plate of an ordinary forging or forming machine. As the inventionprimarily resides in the method and the bending or forming elements, anysuitable device or machine may be employed.

The apparatus for performing the method in its most simple form includesa preforming breakdown die li and complementary forming dies l2 and 13,respectively. either of which may be stationary and either or both ofwhich may be movable and a mandrel or support ll (Figiz) for receivingthe pipe to be bent, indicated by the letter A. It is desirable, and Ihave so illustrated, to have the-breakdown die H movably mounted on thedie I2 and to make said die I! movable; while the die I 3 is stationary.It is also preferable, in some instances, to mount-a circular plug |5 inone end of the pipe A.

As shown in Figure 1, the movable .die |2 is suitably fastened to atransverse reciprocable head IG so as to be horizontally reciprocableabove the bed plate N. This head may be part of a ram, plunger or thelike, and is reciprocated in the usual manner, such as by hydraulicmechanisms now being'commonly employed.

The die |2 is formed with converging, upright side walls ll to provide areduced outer end having an upright face it .which is transverselycurved and is provided with a transverse medial sink or recess I!substantially semi-circular in cross-section. A block housing 20 isfastened on top of the die 12 and a right-singular hanger 21,

preferably formed from a vround bar, has one an angular lug or hook 23(Fig. 1) which engages over one of the upright walls 11 'is formed onone side thereof. When the breakdownA die 11 is not in use it may bepulled outwardly, swung upwardly and then pushed back so as to rest ontop of the die 12. v

The breakdown die is formed with a receding surved face having atransverse medial sink' or recess which is substantially semi-circularin ycross-section and recedes longitudinally inwardly from its outer orforward end (Fig. 1) toward its inner end. 'This provision is made sothat initial-ly the outer end portion of the sink 25 will receive theouter end of the pipe A and gradually make contact with the surface ofthe pipe, as the die 12 is moved toward the die 13, thus assuring auniform and smooth preforming.

As is'clearly shown in Figures l and 2, the die 13 is mounted on atransverse head 26 which also carries a mandrel block 21. The elements13, 26

shoulders against the face 31 and is thus rigidly supported. The mandrelis thus held in position to project into and support the pipe A. Themandrel is generally cylindrical and is of a diameter substantiallyequal to the internal diameter of the pipe to be bent. As illustrated indetail in Figures 3 to 7, inclusive, the mandrel is provided with acurved face 34 at its outer end, which face is curved longitudinally soas to engage the inner -wall of the completed pipe-bend at its medialportion opposite the sink 30. This is accomplished by the transversecontours shown in Figures 4to '1, inclusive.

and 21 may be made integral or separately, the v details beingunessential. The die, block and head rest upon and are suitably fastenedto a transverse breast 28 which may be adjustable, as is customary, butwhich is secured so as to be tationary. The outer end of the die 13 isflared, being formed with atcurved face 23 and a transverse medialsink'or 'recess 30 which is substantially semi-circular incross-section.

The die faces 13 and 29 and the sinks 19 an 30 are all struck onconcentric arcs having a common center. These arcs are designed for theparticular degree of the' pipe-bend desired to be made, and varyaccordingly. However, the arcs are greater than the desired arc or curveof the pipe-bend so as to allow for contraction of said pipe-bend uponcooling thereof. The sinks are given such depths as to cause the faces18 and 28 to come together when the pipe-bend is completed, at whichtime said pipe-bend completely and closely fills said sinks. By such anarrangement, pinching or creasing of the pipe is avoided and a smoothbend is made. Of course, the crosssectional radius or diameter of eachsink is substantially equal to the external diameter of lthe pipe.

By while the central portion of each sink 19 and 30 is curved tothe-degree to give the desired bend, the legs or portions, extendingfrom each end thereof, are tangential thereto. This produces a pipe-bendor tum wherein the bend or are is confined to the central or medialarea. x'I'his is highly important, because it contributes to the forgingof a short bend having a small radios as well as the maintenance ofsubstantially uniform wall thickness.

The mandrel block 21 is formed with a vertical side face 31 disposedtransversely at substantially a right angle to the longitudinal axis ofthe adjacent tangent of the sink 30.' As is clearly shown in Figure 2,the face 31 is provided with a socket 32 for snugly receiving a reducedshank 33 formed on the inner end of the mandrel 14, which latterobserving Figure 2, it will heZ noted that i The flrst step of themethod is the cutting of the pipe to the desired length and it is notedthat the ends of the pipe are square or extend at a right angle to theohgitudinal axis of said pipe. In order to fa tate handling of the pipe,the plug 15 is inserted in its outer end and is provided with anintegral handle 35. When the bend is started, the pipe is suitablyheated to forging temperature, as will be vhereinafter explained, andthe workman holding said pipe by the handle 30 telescopes'it over theinandrel 14 so as to place' ment, the contact of the4 sink 25 with thepipe gradually increases and thus 'produces a more or less rollingaction as 'the pipe is gradually bent. Due to the outer end of the sink25 being substantially parallel to. the axis of the pipe, the engagementof said end with the outer end portion of said pipe will force thelatter toward the far or outer end of the sink 30 of the stationary die.Thus, creeping or movement of the pipe upon the mandrel toward the face31 of the block 21, which would be the result of initial engagement ofthe sink 13 of the die 12 with said pipe, as well as consequentoff-center displacement of the bend are avoided. Also, a greater portionof the i' sink 25 more rapidly engages the outer' end portion of thepipe so as to aid in supporting the same than would the sink 13 if itwas initially engaged with said pipe, whereby distortion of the outerend portion of the pipe is held to a, minimum and the formation timematerially reduced. However, it is possible to eliminate the use of thebreakdown die 11 by positively holding the pipe in the desired positionand employing great care in the initial bending thereof, although theOperating period isl iengthened. -It is noted Vthat the plug 15 tends toprevent distortion of the end portion of the pipe. The prebendingoperation is continued' until the face 2l of 'the die 11 engages theface 29 of the die 13. The die 12 is then retracted.

At this point in the operation,y it is sometimes desirable or necessaryto reheat the pipe. In this event, the plug 15 is withdrawn from thepipe .which is then removed from the mandrei 14, said plug beingreinserted in the same end of said pipe to facilitate lhandling thereof.The pipe is then again heated to forging temperature and said heatedpipe is replaced in the proper position uponV the mandrel. Thebreakdownj die 11 is pulled outwardly, swung up and then pushed backsoas to be supported on top of the die; 12, which die is again movedtoward the die 13 and into engagement with the prebent pipe. The forwardmovement of the die 12 is continued until anses the same is placed in asuitable furnace (notl shown) after which the end of said pipe oppositethe plug is telescoped upon the mandrel so as to properly position thesame. It is noted that the initial or prebend of the pipe will tend toassure proper positioningof the same upon the mandrel relative to thedies andthat the breakdown die I I is swung out of the way. The die 12is then moved forwardly into engagement with the prebent pipe and thisforward movement is continued until the face i8 engages the face 29. Atthis point, the bend is completed and the bent pipe may be removed fromthe mandrel in the manner hereinbefore set forth upon retraction of thedie |2.

As' is clearly shown in Figure 14, the completed pipe-bend has a shortarc of relatively small radius and comparatively long tangents. Also,the original wall thickness is retained and especially at the outermedial portion of the pipebend. If desired, the axial or center arc ofthe pipe-.bend may have a radius as small as one (1) or one and one-half(11/2) times the nominal diameter of the pipe. It is pointed out thatwhen the bend has a long tangent at one or both ends,

such radius is virtually unobtainable by present known methods andapparatuses. Since the formation of the pipe-bend is accomplishedwithout thinning the wall of the original pipe, the stock forming theouter end portions of said pipebend will fiow or be forced inwardlytoward the center of the outer medial portion thereof so as to shortensaid outer end portions. Thus, it is necessary to cut the ends of thepipe-bend at a right angle to the axes of the tangents as shown at 35(Fig. 14) after the lforming of Said pipebend.

T-he heating of the pipe, hereinbefore and hereafter referred to, may beaccomplished in any suitable manner, such as by a furnace (not shown),and the forging temperature is largely determined by thetype of metal oralloy from which said pipe is formed. Ordinarily, the forgingtemperature is between twelve hundred (1200) and twenty-four hundred(2400) degrees F.; however, inl forging pipes of non-ferrous metals, thetemperature may be much lower and may be even as low as five hundred(500) degrees F. Also, the application of heat to the pipe may begradated, whereby one portion of said pipe may be heated to a lesserdegree than the remainder thereof. This heat gradation is especiallyimportant in connection with that portion of the pipe which is to form-or which forms the outer medial portion of the pipe-bend. By holdingthe temperature of such pipe portion to a minimum, stretching andconsequent thinning of said portion upon bending of the pipe ismaterially reduced without impairing the plasticity of the remainder,especially theinner medial portion, of said pipe. Thus, a substantiallyuniform flowing or reshaping of the aforesaid pipe remainder and themaintenance of a uniform wall thickness is greatly assisted, which wallthickness is approximately equal to the original wall thickness of thepipe.

In Figures 8 to 10, I have shown another form of apparatus for formingthe pipe-bend, wherein a. pair of opposed power-operated mandrels 40 and4| are employed. These mandrels may bo operated by any suitable means,such as manual, mechanicai or hydraulic, and I have chosen to iliustratea hydraulic mechanism. Each mandrel is substantially identical and ismade integral with or is rigidly secured to a piston rod 42 extendingforwardly from a non-rotatable piston head 43 which is reciprocallymounted within a cylinder 44. A flat, rectangular base member 45,adjustably secured to the bed plate lo, supports each cylinder and itsmandrel in a plane parallel to said bed plate. The mandrels aresubstantially duplicates of the mandrel I4, except as to the shank 33,and have identical curved outer faces 34. A transverse guide bracket 31issecured to one end portion of the base 45 by suitable cap screws 38 tosupport the outer end of each mandrel. As is clearly shown in Figure 13,the base 45 overlies the bed plate and is secured thereto by a pluralityof small bolts 48. A shank or post 4'| depends from the base through acomplementary opening or socket 48 formed in the bed plate and has asuitable bolt 49 screwthreaded into the lower end thereof. For clampingthe base to the bed plate, an annular element or washer 50 is confinedupon the bolt 40 between its head and the bottom of said bed plate. Ifdesired, a plurality of sockets 48, as well as small openings 45a forreceiving the small bolts 46, may be formed in the bed plate to permitadjustment of each base in an arc relative to the dies as shown inFigure 8, the adjustment being accomplished by removing said bolts 45and the bolt 49 and moving the base to the desired position. The detailsof the adjustments are immadesirable to cool the mandrels and this maybe readily accomplished by providing an internal return duct in eachmandreL'the cooling fluid or medium being supplied by a hose 55 andexhausted by a similar hose 51. The duct extenos around the end portionof the mandrel in close proximity to its curved face 34 as it isextremely important to chill the portion of the pipe which is to formthe outer medial portion of the pipebend, as will-be hereinafter morefully explained.

After being cut to the desired length, the pipe A is heated to theproper forging temperature and then placed upon either the mandrel 40 orthe mandrel 4l, one of which has been moved to its fully projectedposition by its respective piston 43 through manipulation of the pilotvalve 5l. A plug 58, similar to the plug l5 and having an integraloff-set handle 59, is inserted in one end of the pipe to facilitatehandling thereof and the opposite end of said pipe telescopes theprojected mandrel, whereby the pipe engages and is properly positlonedrelative to thesink 30 of the stationary die i3. With the breakdown diell being in place as shown in Figure 8, the die |2 is moved toward thestationary die |3 so that the outer end of the sink 25 of said breakdowndie engages the outer end portion of the pipe A. As has beenhereinbefore set forth, the continued forward movement of the dies lland l2 will cause the contact of the sink 25 with the pipe to graduallyincrease and thereby graduande ally bend said pipe and force its outerend portion into engagement with the outer or far end forwardly towardthe die |3 and into engagement,

with the pipe, such movement being .continued until the face |8 of saiddie |2 engages the face 29 aspshown in Figure 9. .At this point in the 4operation, the projecting mandrel upon which shown in Figures 8 to 10.With the exception of the mandreis, the apparatuses are substantiallyidentical. Complementary, short mandreis 00 and GI are substituted forthe mandreis 40 and 4I. The inner portion of each mandrel is enlarged indiameter to provide a reduced outer end portion or shank 62, having adiameter equal to the internal diameter of the pipe. and an annular.radial shoulder G3 substantially at the medial portion of said mandrel.It is preferable to bevel-or taper the outer extremity of each outershank 62 as shown at 64 so as to provide space 4! is ejected so as totelescopewithin the opposite end of the pipe as shown in Figure 10,thereby rounding out the interior of said pipe and particularly theouter end portion thereof. Manifestly, this end portion of the pipe isslightly distorted by the bending operation due to the absence of themandrel 4l, whereas the mandrel 40 has prevented distortion of theopposite end portion of said pipe. The ends of the completed pipe-bendare cut off at a right angle to the longitudinal axis of the tangents ofsaid pipebend, as hereinbefore set forth.

As has been hereinbefore set forth, the mandrels are provided with ducts55 for receiving a cooling fluid or medium and each duct passes in closeproximity to the curved face 34 of its respective mandrel. Thus, thecurved faces 34 are cooled and the portion of the pipe, which iscontacted by said faces and which is to form the outer medial portion ofthe pipe-bend, is chilled so as to prevent stretching and consequentthinning of said portion during the bending operation. Due to thedisposition of the inlet hose 5G, it is manifest that the cooling mediumwill be relatively Warm by the time it passes around the end of themandrel and will have little or no effect upon the inner medial portionof the pipe-bend. Thus, the inner medial portion of the pipe is free' tofiow so as to be displaced or reshaped uniformly and thereby produce apipebend of uniform wall thickness. Of. course, the

ma'ncilrels 40 and 4| could be used without being cooled, but theresults would not be as satisfactory and it is very probable that theouter medial portion of the pipe-bend might b'e stretched and thinned.Although not illustrated, it is readily apparent that the mandrel |4 ofthe first form of the invention could' be cooled in the same manner asthe mandreis 40 and 4l.

Of course, it may be necessary or desirable to reheat the pipe toforging temperature after the prebending thereof. However, it is usuallypossible to eliminate such heating step as well as the reheating priorto the final bending or forging operation. Thus, at least one, andpossibly two, heating steps are rendered unnecessary with 'a consequentsaving of time and expense by the apparatus shown in Figures 8 through10.

Figures 11 and 12, this upsetting may be accomplished by an apparatusvery similar to that to accommodate the upset portion of the bend and toeliminate any possibility of marring the interior of the pipe-bend.- Itis noted that the diameter of the enlarged inner portion of each mandrelis substantially equal to the external diameter of the pipe, wherebysaid mandrel may be inserted into the space formed by the sinks 18 and30 when the dies |2 and |3 are closed or brought together.

After the formation of the pipe-bend, the ends thereof are cut atl anangle greater than a right angle so that the outer longitudinal portionof each tangent is of greater length than and projects beyond its innerlongitudinal portion. The pipe-bend is then heated to the desiredforging temperature and placed in the sink 30 of the stationary dieI3'and the sink |9 is brought into contact with said pipe-bend by movingthe die |2 toward said die |3 until the die faces IS and 20 are inengagement. Thus, the pipe-bend will .be coniined within and held inplace by the coaction of the sinks IB and 30. With the pipebend heldfirmly in position, the mandrels 60 and BI are simultaneously projectedso as to cause the outer Shanks 62 thereof to enter the bore of saidpipe-bend. As the projection of the mandreis progresses, the shoulders63 will enter the space formed by the sinks IQ and 30 and engage theends of the pipe-bend (Fig. ll) Due to the greater length of the outerlongitudinal portion of the pipe-bend, the engagement of the shoulder 63will apply pressure to said portion and thereby force the ends thereofinwardly toward its'center. Thus, the outer medial portion of thepipe-bend will be upset so as to increase the thickness thereof. Anydesired thiclrness of the' upset portion may be attained up to one andone-half (11/2) times the normal thickness of the pipe or pipe-bend.

Due to the engagement of the mandreis within the pipe-bend, there is nodistortion thereof and the original wall thickness and diameters areretained with the exception of the upset portion. The inner portion ofthe pipe-bend is unaffected by this upsetting step, since the endsthereof are not engaged by the shoulders 63 and no pressure is appliedthereto during such-step. Due to the provision of the shoulders 63, theends of the completed upset pipe-bend will be square or extend at aright angle to the longitudinal axis of the tangents of said pipe-bend.This is accomplished by the continued projection of the mandrels totheir fully-extended position, whereby the shoulders are in fullengagement with the ends of the pipe-bend.v After the foregoingupsetting step, the mandreis are retracted so as to withdraw the samefrom the pipe-bend and the die l2 is returned to its original positionso as to permit removal of said pipe-bend. Although not illustrated, itis manifest that the cooling illustrated in connection with Figures 8 to10 might be employed in the upsetting step.

The foregoing description of the invention is expianatory thereof andvarious changes in the size, shape and materials, as well as in thedetails of the illustrated construction may be made, within the scope ofthe appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. The method of forming pipe bends with tangential ends which includes,heating a suitable right' line length of pipeI then rigidly andicmmovably supporting one end and a medial portion of the pipeinteriorly and exteriorly while the opposite end of the pipe and amedial portion of the pipe are unsupported, then preliminarily bendingthe unsupported end of the pipe while immovably and rigidly supportingsaid pipe, and then compieting the bending of the pipe by pressing theentire bend between arcuate surfaces having the curvature of thecompleted bend and maintaining the inside wall of the bend ofsubstantially uniform thickness.

2. An apparatus for forming pipe bends includl ing, a support, astationary rigid die mounted upon the support and having a sink providedwith an outwardly directed arcuate medial portion and end portionstangential thereto, a die mounted on the support to move toward andengage the stationary die and having a sink provided with an inwardlydirected arcuate medial portion and end portions tangential thereto,said dies having complementary engaging faces, a mandrel carried by thesupport mounted to telescope the pipe to be bent and having a curvedface conforming to the arcuate medial portion of the sink of the movabledie and extending approximately the entire length of the said diecurvature, and means for moving said movable die toward and from thestationary die while the mandrel is stationary.

3. An apparatus for forming pipe bends including, co-acting die membershaving sinks each formed with a medial curved section and end portionstangential thereto and shaped to the contour. of a completed pipe bendof substantiaily uniform wall thickness, a mandrel adapted to beinserted in a length of pipe to be bent and having at its insertable enda face curved longitudinally and transversely for forming the entireouter bend of the pipe, means for rigidly supporting one of the dies,means for supporting the mandrel in longitudinal alinement with one ofthe tangential ends of the sink of the rigid die, said mandrel beingpositioned to telescope one end of a pipe to be bent and to support saidpipe end in the alined die sink, and means to move the other die intoengagement with the rigid die to bend the pipe and confine it in the diesinks.

4. An apparatus as set forth in claim 3 and a 10 removable plug forinsertion in the unsupported end of the pipe.

5. An apparatus as set forth in claim 3 and a break-down die removablymounted on the movabie die to overhang one end of the sink thereof.

6. An apparatus as set forth in claim 3, and a second plunger having aface curved complementaryV to the face of the first named plunger, meansfor withdrawing the flrst named plunger from the bent pipe, and meansfor moving the second mandrel into the bentpipe after the first namedmandrel has been withdrawn.

7. An apparatus for forming pipe bends including, a mandrel having aface curved transversely and longitudinally to support the entire outerbend of a pipe bend having tangential ends, and a pair of dies havingcomplementary sinks provided with medial portions curved concentricallyto the curved face of the mandrel adapted to be moved together to bend apipe supported at its medial and one end portion on said mandrel.

CLINT CROSS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 472.504 Kitzrniller Apr. 5, 1892951,717 Andres Mar. 8, 1910 953,253 Brinkman Mar. 29, 1910 1,0l8,676Mulvey Feb. 27, 1912 1,043,334 McKee Nov. 5, 1912 1,099,669 RuckstinatJune 9, 1914 1,198,18'7 Brinkman Sept. 12, 1916 1,430,856 Slick Oct. 3,1922 1,672,068 Laing June 5, 1928 1,781,567 Bohling Nov. 11, 19301,816,218 Henry et al July 28, 1931 1,857,583 Bohling May 10, 19321,903,436 Brown Apr. 11, 1933 1,908,373 Loepsinger May 9, 1933 1,923,272Maroto Aug. 22, 1933 1,931,306 Taylor Oct. 17, 1933 1,931,307 TaylorOct. 17, 1933 1,958,447 Quartz et al May 15, 1934 1,960,788 Maroto May29, 1934 1,978,452 Flodin Oct. 30, 1934 1,996,838 Snell Apr. 9, 19352,038,165 Criley Apr.|21, 1936 2,149,508 Coe Mar. 7, 1939 FOREIGNPA'I'ENTS Number Country Date 276,537 Germany July 14, 1914

